Portable, battery-powered computers have become increasingly popular over the last several years due to their light weight and small size that permit them to be easily hand-carried in an ordinary briefcase and used by business travelers in cramped spaces, such as on airline seat back trays, lacking electrical plug-in facilities. In fact, a particularly small type of portable computer, the notebook computer, is very popular, generally having dimensions of 8.5".times.11" and a weight of less than 8 pounds. For purposes of this discussion, "portable" and "notebook" are synonymous terms. The modern portable computer typically incorporates both hard and floppy disk drives, a monitor screen built into its lid portion, and a keyboard built into its main body portion. It is thus a fully self-contained computer able to be conventionally used, for at least short periods of time, in situations and locations in which the use of a much larger desktop computer is simply not feasible.
As is well-known, however, even state-of-the-art portable computers have certain limitations and disadvantages, compared to their much larger desktop computer counterparts. For example, the compact keyboard of a portable computer is often considerably less comfortable to use for extended periods of time compared to the more spacious separate keyboards normally provided with desktop computers.
Additionally, to reduce the space requirements for the typical portable computer keyboard, many of its keys, that would have but a single function on a desktop computer keyboard, are provided with multiple functions which can be confusing to user switching back and forth between desktop and portable computers. Moreover, compared to its desktop computer counterpart, the portable computer monitor typically does not provide its viewer with as sharp a display image. After an extended computing session, this reduction in display clarity can cause the computer user to experience at least some degree of eye strain. Another disadvantage of portable computers is that, due to their small size, they typically do not provide access for expansion cards such as, for example, network, sound, graphics accelerator and multimedia cards which desktop computer units are conventionally configured to receive.
Because of these short comings inherent in portable computers, it is a common practice for their owners to also purchase a desktop computer system for home or office use. A typical scenario for these two-computer owners, after returning home after using their portable computer on a business trip, is to transfer their files, data, spreadsheets and the like from their portable computer to their desktop computer and continue working on the initiated project or projects using the larger and more comfortable desktop peripheral equipment such as the external monitor, keyboard and mouse.
The task of effecting this state of transfer from a portable computer to the desktop computer (and vice versa in preparation for a subsequent road trip) is not a particularly convenient one for the computer user. It is typically accomplished by the often time consuming method of (1) inserting a floppy disk into the portable computer, (2) copying a portion of the data from the portable computer hard drive onto the inserted floppy disk, (3) removing the floppy disk from the portable computer (4) inserting the removed floppy disk into the desktop computer, (5) copying the data from the floppy disk onto the hard drive of the desktop computer and then (6) repeating steps (1) through (5), as necessary, until all of the desired data is transferred from the portable computer to the desktop computer.
Alternatively, various software is available for use in a portable computer to down load data therefrom to a desktop computer through a cable interconnected between the serial ports on the portable and desktop computers. This procedure, while somewhat more convenient than laboriously shuffling floppy disk back and forth between the two computers has other disadvantages. For example, it requires the additional purchase and installation of the transfer of software which occupies space in the portable computer hard drive-space which is often at a premium in the relatively small hard drives typically provided in portable computers.
Moreover, each time data has to be transferred from the portable computer to the desktop computer, a cable must be interconnected between the two computers and subsequently disconnected. This can be a rather awkward task since the serial port on a desktop computer is typically located on its backside in the midst of a jumble of other cables.
In addition to the inconvenience of these conventional methods of transferring data back and forth between portable and desktop computers there is, of course, the considerable expense entailed in purchasing two complete computer system to provide both the compactness and portability of a portable computer and the greater capacity and use comfort of a desktop computer. Some of this expense may be avoided by purchasing (in addition to the portable computer) only desktop computer peripheral equipment--such as a monitor, keyboard, mouse and external hard drive--for home or office use.
When the user works at his home or office station, he connects the portable computer to the desktop computer peripheral equipment, using the necessary interconnect cables to fashion a highbred computer system utilizing the portable computer central processing unit ("CPU") in conjunction with the desktop computer peripheral devices. While this alternative approach is less expensive than purchasing two complete computer system, it is highly inconvenient due to the number of cables that must be interconnected between the portable computer and the desktop peripherals to "construct" the hybrid system and later be disconnected to free the portable computer for travel use. Additionally, the jumble of interconnect cables sprawling across the desk or table area creates a decidedly disorderly and unattractive work station.
In response to these problems and inconveniences, interconnect structures commonly referred to as "docking stations" have been previously proposed. A docking station is basically a housing structure, considerably larger than a portable computer and designed to be left in place on a home or office desktop, to which the portable computer may be removably connected by releasably interengaging mating plug and socket portions (also called "connectors") fixedly secured to the portable computer and the associated docking station.
The docking station is typically connected to external desktop peripheral devices, such as a monitor, keyboard and mouse, that remain in place on the desktop work station. Disposed within the docking station housing are various components that serve to operatively connect the portable computer to these desktop peripheral devices when the portable computer is plugged into the docking station. However, the docking station is not provided with a CPU. Instead, when the portable computer is "docked" in this manner, its CPU is utilized in the resulting desktop computer work station and the desktop keyboard, monitor and mouse are used in any subsequent desktop computing task. After these tasks are completed, the portable computer can simply be unplugged from the docking station and carried away for use of the removed portable computer in its usual self-contained mode.
Compared to the previous necessity of purchasing a complete desktop computer system in addition to a portable computer, the use of this docking station concept provides several distinct advantages. For example, since the docking station is not furnished with its own CPU (using, in place thereof, the portable computer's CPU) the overall cost of providing both portable and home or office-based computer work stations is substantially reduced.
Additionally, the previous inconvenience of transferring data from the portable computer to the desktop system is essentially eliminated since the requisite notebook/desktop computer interface with its data transfer is achieved simply by plugging the portable computer into the docking station (which may have an internal hard drive or be connected to an external hard drive) without the need for switching floppy disk back and forth or using an external interconnection cable. Moreover, from a connection convenience standpoint, the use of the plug-in docking station is clearly preferable to laboriously connecting the portable computer directly to desktop peripheral devices using several separate interconnect cables.
Despite their cost reduction and convenience advantages, previously proposed docking stations have tended to have certain problems associated therewith relating to their physical connection to the associated portable computer. For example, since the relatively small plug-in interface between the docking station and the portable computer must effect a multitude of electrical connections between the internal operating components in the portable computer and the docking station housing, mating high density pin connector structures (one on the portable computer and one on the docking station) are typically used to provide the plug-in computer/docking station mechanical interconnect.
A typical method of creating this interconnection is to place the portable computer on the docking station, with the mating pin connectors in a facing, spaced apart relationship with one another, and then manually pushing the portable computer toward the docking station connector pin structure to create the plug-in connection. The need to precisely align the facing connectors, coupled with the high mating force requirement associated with these high density pin connectors, typically requires that this manual connection task be carefully and precisely performed to avoid potential damage to the connector pin structures. The same care must be exercised, and a considerable amount of manual force exerted, in disconnecting the portable computer from the docking station to avoid connector pin damage.
Another problem typically associated with conventional manually operable docking station systems is that it is possible to attempt to dock the portable computer while the computer is in a normal operating mode and the docking station is off, or vice versa. A "normal operating mode" is defined as a mode in which the portable computer's CPU is fully functional, executing instructions and accessing the various buses. The normal operating mode is as opposed to a "suspend mode" (or "sleep mode") wherein the CPU is stopped and the buses are inactive or an "off" mode wherein the portable computer is powered down. An attempt to dock the portable computer while it is still in a normal operating mode creates a voltage mismatch between the mating portable computer and docking station connectors. This voltage mismatch has two undesirable effects: (1) the user's data stored in the main memory of the portable computer is highly likely to be corrupted or destroyed and (2) input buffers and other components within both the portable computer and the docking station may be damaged if the voltage mismatch persists.
Ser. No. (DC-00275) is directed to a portable computer/docking system employing a carrier under motor control to overcome the insertion force problems noted above. The portable computer/docking station includes a photodarlington detector to detect whether a power indicator on the portable computer is lit, indicating that the portable computer is in its normal operating mode. If the portable computer is in its normal operating mode, as indicated by the power indicator being lit, the docking station reverses its motor to eject the portable computer, thereby refusing its docking until the user places the portable computer into a suspend mode or turns the computer off.
It is very desirable, however, to have the docking station accept the portable computer in its normal operating mode for docking instead of rejecting it out of hand. The portable computer should be able to detect when it is about to be docked and should be able to automatically react by placing itself in a suspend mode before actually docking.